1. Field
The instant invention relates to composite water bed mattress structures which have a thickness, width and length comparable to conventional single, double, queen and king size mattresses. Composite water bed mattresses are generally supported upon a rigid box-like structure and have a weight substantially less than a conventional water bed.
2. Prior Art
In recent years, the bedding industry has developed a hybrid mattress which is a cross between a conventional water bed and a conventional innerspring or foam mattress. These hybrid or composite mattresses have a thin, for example, three inches to six inches in depth, water filled bladder and some means of restraining the bladder laterally. Generally, a foam cushion means rests upon the bladder to insulate the sleeper's body from the water bladder and to reduce some of the vibrations and waves caused by any motion upon the water-filled bladder.
Typical composite water bed mattresses which have been developed in recent years include the structures disclosed in Tinnel, U.S. Pat. No. 4,015,299; LaBainco, U.S. Pat. No. 3,840,921; Tobinick, U.S. Pat. No. 3,702,484; Autrey et al, U.S. Pat. No. 4,062,077; Alsbury, U.S. Pat. No. 3,742,531; Weinstein, U.S. Pat. No. 3,689,945.
The following patents, although directed to a more conventional water bed structure disclose structures which are germane to composite water bed mattress structures. Examples of such patents include Carson, U.S. Pat. No. 3,736,604; Hall, U.S. Pat. No. 3,585,356; and Kretin, U.S. Pat. No. 3,735,432.
Other patents disclosing structures relating generally to water beds or structures which may be adapted in certain aspects to composite water beds include the following: U.S. Pat. Nos. 3,778,852 (Penn); 3,787,908 (Beck); 3,864,768 (Fraige); 4,042,986 (Goodman); 3,581,322 (Marsico); 2,481,833 (Foster); 3,849,814 (Ross); 3,958,286 (Rodinsky); 3,308,491 (Spence); 1,371,362 (Giese); 3,728,747 (Docker); 3,864,767 (Adams).
Each of the above-described patents has certain advantages and disadvantages. For example, in Autrey et al the vertical rigid restraining member is adjacent the bladder and must be substantially the same height as the bladder to avoid pinching the bladder against the upper surface of the rigid restraining member. Thus, if the bladder has a substantial thickness, for example four to six inches, the rigid restraining member height must be about the same height, allowing very little foam cushioning above the restraining member's thin edge inasmuch as conventional composite mattresses have a thickness from about six to eight inches. Thus, the restraining member is readily detected and is uncomfortable to sit upon or to lie upon when a bladder of about four inches or more in thickness is used. If thinner bladders are utilized in the Autrey et al structure then the water bed effect is substantially diminished.
In the Tinnel structure the restraining wall is a unitary foam construction. It is a flexible foam so it is comfortable to sit on, however, once the bladder is filled there is some tendency of the side walls of the structure to bow because the hydrostatic pressures involved. Also, since the foam depresses significantly whenever anyone sits upon an edge, the safety reservoir feature is diminished since the upper level of the liner is then moved to a position lower than the bladder height. In such an event, water spills out if the bladder has a major leak and water has filled the reservoir.
In Kretin et al the rigid retaining members have a substantial vertical dimension which brings a thin edge to a position relatively close to the upper foam surface.